Woven multiply fabrics prepared for use as dryer fabrics or felts are woven completely from one end of the roll to the other with a continuous weave formation. The ends of this fabric may be joined by sewing a suitable pintle seam webbing material across the end width wise. Such webbing customarily has some form of loop or hook configuration on one end which is aligned with the end of the woven fabric and attached as by sewing to one side only of the woven fabric. The webbing may also be joined in such a way that two layers of webbing fit over the end of the woven fabric sandwiching it in between so that all three thicknesses may be stitched together to complete that end of the felt or belt. Another way of joining the belt consists of removing a sufficient number of filling threads to permit folding back warp yarns and hand weaving them back into the body of the fabric thus forming rows of loops for reception of a pintle. U.S. Pat. No. 3,393,115 illustrates a butt spliced joint but such involves substantially increased labor costs.
Felts prepared and joined in the aforementioned conventional ways present problems especially where the webbing is attached by sewing to one side of the woven fabric creating an undesirable lump in the joining area as illustrated in U.S. Pat. Nos. 2,879,580 and 3,335,844. When the fabric is so joined into a belt on the papermaking machine, the joined area constantly strikes the many felt rolls over which it runs causing extra fatigue to set in across the width of the felt creating a bumping and thumping noise problem.
The thickened seam portion of conventional seams bumps when it slaps a roller sending out ripples causing the supported paper to leave the felt and when it returns, a change in the pattern of the paper occurs accompanied by weakened areas. This is particularly unsuitable for fine grade paper.
This condition also places a very heavy strain on the stitching which attaches the webbing to the base fabric since all linear tension pulls from only one side of the felt or belt. This condition causes many felts and belts to come loose from the webbing ruining the felt, which would otherwise be serviceable for an extended period of time, with attendant loss of paper or conveyed stock. With prolonged running time, the exterior thickness of the joined area tends to cause a permanent indention on the face side of the belt or felt which then causes paper sheet marking.
When the webbing is attached equally on both sides of the end of the woven fabric and stitched in this configuration, the noise problem is reduced somewhat, but the fatigue and sheet marking problems are much worse.
The hand woven seam described above has application only on fabrics containing monofilament synthetic warp yarns. Moreover, the procedure for this hand weaving operation is very time and cost consuming and is subject to operator fatigue and error, resulting in the formation of a row of joining loops which have varying yield to load properties.